Superman is locked in a battle with Lex Luthor, who is threatening to melt the polar icecaps and flood the world. Meanwhile, in Gotham, the Joker is going to gas the city and meanwhile in space, the Green Lantern is getting ready to defend against the invading Sinestro Corps. All of these examples have villains that are exhibiting differing levels of threat.

You can class various villains on tiers of the type of threat they present to the world and the heroes. The Sorting Algorithm of Evil will usually ensure that the hero's successive opponents will each be higher on the scale than the last, but, due to the SAoE's caring about effectiveness as well as scope, not always. In general, the hero will also have the same potential for destruction as his villains, but usually is slightly below them, because underdogs are more relatable. Having a wild range of villains may help avoid causing a feeling that The World Is Always Doomed because Evil Only Has to Win Once. Having a hero with a Story-Breaker Power usually upsets this dynamic, or forces a jump in villain up the scale.

Multidimensional Threat: Just to one up those small-timers above, these guys won't stop at a single universe; they'll cross time and space to either take control or just smash all of reality to pieces. See Multiversal Conqueror.